Vacuum IG units are known in the art. For example, see U.S. Pat. Nos. 5,664,395, 5,657,607, and 5,902,652, the disclosures of which are all hereby incorporated herein by reference.
FIGS. 1-2 illustrate a conventional vacuum IG unit (vacuum IG unit or VIG unit). Vacuum IG unit 1 includes two spaced apart glass substrates 2 and 3, which enclose an evacuated or low pressure space 6 therebetween. Glass sheets/substrates 2 and 3 are interconnected by peripheral or edge seal of fused solder glass 4 and an array of support pillars or spacers 5.
Pump out tube 8 is hermetically sealed by solder glass 9 to an aperture or hole 10 which passes from an interior surface of glass sheet 2 to the bottom of recess 11 in the exterior face of sheet 2. A vacuum is attached to pump out tube 8 so that the interior cavity between substrates 2 and 3 can be evacuated to create a low pressure area or space/gap 6. After evacuation, tube 8 is melted to seal the vacuum. Recess 11 retains sealed tube 8. Optionally, a chemical getter 12 may be included within gap 13.
A typical apparatus for pumping down and sealing of the VIG unit is disclosed in U.S. Pat. No. 7,244,480, the entire contents of which are incorporated herein by reference. In the FIG. 3 embodiment of the '480 patent, for example, while the whole VIG unit is in the atmosphere, the evacuation was accomplished through a pumping port tube using an upside-down cup connected to the vacuum system. Once the pump-down is completed, the pumping port is sealed by tipping off the tube using a device, which can be either a wire heater, or focused IR source, or a laser, or other heating devices.
Although this approach appears to be effective in a batch type of operation, it is disadvantageous in an in-line type of VIG production system. For example, the vacuum line has to travel the whole distance with the VIG unit, which results in complicated machinery design and more potential machine failures.
Thus, it will be appreciated that there is a need in the art for improved techniques for evacuating and/or sealing vacuum IG units.
An aspect of certain example embodiments relates to providing staged pressure reductions, pump-out port sealing, and staged pressure increases via a unitized oven.
In certain example embodiments of this invention, a method of making a vacuum insulating glass (VIG) window unit is provided. An oven including a pressure reducing zone, a port sealing zone, and a pressure increasing zone is provided. Inserted into the oven is a unit comprising first and second substantially parallel spaced-apart glass substrates, a gap defined by an area between the spaced apart substrates, and a pump-out port formed in the first or second substrate. The pressure reducing zone of the oven is evacuated to at least one reduced pressure to also evacuate the gap of the unit, each said reduced pressure being below atmospheric. The port sealing zone is evacuated to a final evacuation pressure to further evacuate the gap or recess of the unit below the at least one reduced pressure. The pump-out port of the unit is sealed during or after the port sealing zone evacuation in forming a vacuum insulating glass (VIG) unit. The pressure increasing zone is vented so as to bring a pressure of the pressure increasing zone closer to atmospheric.
In certain example embodiments, a method of making a vacuum insulating glass (VIG) window unit is provided. Inserted into the oven is a unit comprising first and second substantially parallel spaced-apart glass substrates, a recess or gap defined by an area between the spaced apart substrates, a pump-out port formed in the first or second substrate, one or more edge portions of the first and second substrates to be sealed, and a fit provided at least partially between the first and second glass substrates for sealing said one or more edge portions to be sealed. The unit is pre-heated substantially in its entirety to at least one intermediate temperature, each said intermediate temperature in the pre-heating being below a melting point of the first and second substrates and below a melting point of the frit. Localized near infrared (IR) inclusive heat is provided to the unit proximate to the edge portions to be sealed so as to at least partially melt the frit, the localized near IR heat being provided to the unit such that at least some areas of the unit not proximate to the edge portions to be sealed are kept at a temperature(s) below fit-melting temperature. The unit is cooled and the frit is allowed to harden. The gap of the unit is evacuated to at least one reduced pressure, each said reduced pressure being below atmospheric. The gap of the unit is further evacuated to a final evacuation pressure, the final evacuation pressure being below the at least one reduced pressure. The pump-out port of the unit is sealed during or after the evacuating of the gap to the final evacuation pressure in forming a vacuum insulating glass (VIG) unit. An area around the unit is vented so as to bring a pressure of the area closer to atmospheric.
In certain example embodiments, an apparatus for evacuation and sealing for vacuum insulating glass units is provided. An entrance zone receives a unit comprising first and second substantially parallel spaced-apart glass substrates, a gap defined by an area between the spaced apart substrates, and a pump-out port formed in the first or second substrate. A pressure reducing zone evacuates a pressure therein to at least one reduced pressure to also evacuate the gap of the unit, each said reduced pressure being below atmospheric. A port sealing zone evacuates a pressure therein to a final evacuation pressure to further evacuate the gap of the unit below the at least one reduced pressure, and seals the pump-out port of the unit during or after the evacuating of the port sealing zone in forming a vacuum insulating glass (VIG) unit. A pressure increasing zone increases a pressure therein so as to bring the pressure of the pressure increasing zone closer to atmospheric.
In certain example implementations, such an apparatus may comprise a pre-heating zone for pre-heating the unit substantially in its entirety to at least one intermediate temperature, each said intermediate temperature being below a melting point of the first and second substrates and below a melting point of the frit; an edge sealing zone including a localized heat source for providing localized heat to the unit proximate to the edge portions to be sealed at a frit melting temperature, the frit melting temperature being sufficiently high enough to melt the frit, the localized heat being provided to the unit such that areas of the unit not proximate to the edge portions to be sealed are maintained at a temperature close to an intermediate temperature; and a cooling zone of the oven for cooling the unit in its entirety to at least one reduced temperature and allowing the frit to harden.
In certain example implementations, a single chamber or a single set of chambers may be configured to provide the functionality of multiple zones. In certain example implementations, the zones may be arranged in line and in the following order: the entrance zone, the pre-heating zone, the edge sealing zone, the cooling zone, the pressure reducing zone, the port sealing zone, and the pressure increasing zone.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.